Electrical circuit



Feb. 2, 1954 P. w. STUTSMAN 2,668,259

ELECTRICAL CIRCUIT Filed Feb. 16, 1950 FIG.

PAUL W$7UTSMAN INVENTOI? I I Wig Patented Feb. 2 1954 ELECTRICAL CIRCUIT Paul W. Stutsman,

Mass.,

Needham, Mass., assignor to Raytheon Manufacturing Company,

a corporation of Delaware Newton,

Application February 16, 1950, Serial No. 144,451 8 Claims. (01. 315-97) l This is a continuation-in-part of my copending application, Serial No. 669,048, filed May 11, 1946, now abandoned.

This invention relates to electrical circuits, and more particularly to circuits for starting, and for supplying operating voltages to fluorescent lamps.

An object of this invention is to provide a starting circuit for fluorescent lamps, whereby such lamps may be started substantially instantaneously.

Another object is to provide a fluorescent lamp supply circuit which will absorb a minimum amount of power from the power source.

A further object is to provide a fluorescent lamp supply circuit by the use of which flickering of said lamps is eliminated.

A still further object is to devise a circuit whereby a plurality of fluorescent lamps may be operated in such a manner as to provide a maximum amount of light at the expenditure of a minimum amount of power.

The foregoing and other objects of the invention will be best understood from the following description of some exemplifications thereof, reference being had to the accompanying drawing, wherein:

Fig. 1 is a diagrammatic representation of one means for carrying out the invention; and

Fig. 2 is a diagrammatic representation of another means for carrying out the invention.

A fluorescent lamp I consists of an elongated sealed bulb '2, having filaments 3 and 4 sealed into opposite ends thereof, and containing a lowpressure gaseous atmosphere. Filaments 3 and 4 are coated with an electron-emissive material.

Leads 5 and 6 are connected to a source of alternating current, for example, a commercial supply of the order of 115 volts. Lead 5 is connected directly to one of the A. C. input terminals I of a rectifying and voltage doubling circuit indicated generally by 8, while lead 3 is connected through a switch 9 and a resistor I9 of low resistance to the other input terminal II of said circuit 8.

Circuit 8 includes a pair of gaseous-discharge devices I2 and I3, said devices being oppositely connected to terminal I I. These devices are preferably of the Y4 ionically-heated cathode type, each having a cathode, an anode, and a starting anode. Thus, device I2 includes a cathode I4, an anode I5, and a starting anode I 5, said starting anode being connected to main anode I through a resistor II.' Device I3 includes a cathode I8, a main anode I9, an d astarting anode 29, said starting anode 29 being connected to main anode I9 through a resistor 2 I. Cathode I 4 of device I2 and main anode I9 of device I3 are connected to A. C. input terminal II. Main anode I5 of device I 2 is connected to one terminal of a condenser 22, the otherterminal of said condenser being connected to A. C. input terminal I. Cathode I8 of device I3 is connected to one terminal of a condenser 23, the other terminal of said condenser also being connected to A. C. input terminal I. The negative D. C. out-' put terminal 24 of circuit 8 is connected to an ode I5, while the positive output terminal 25 of circuit 8 is connected to cathode I8.

When switch 9 is closed to complete the circuit from the A. C. source to input terminals I and II, are discharges are established in tubes 52 and I3, and the condensers 22 and 23 are charged in alternate halves of the cycle through rectifier tubes I2 and I3. The condensers are connected in series, so that their voltages add, giving a direct voltage across terminals 24 and '25 that approaches twice the crest alternating voltage.

Terminal 25 is connected through a. ballast resistor 26, for example, a 40-watt lamp, to filament 4 at one end of fluorescent lamp I. Negative terminal 24 of circuit 8 is connected through operating winding 21 of a relay 28, to one end of filament 3, the other end of said filament being connected to one of a pair of normally closed contacts 29 carried by relay 28. The other of said contacts 29 is connected, through a resistor 30, to filament 4. I

To start the discharge in fluorescent lamp I, switch 9 is closed. As stated above, this causes a direct voltage, of approximately twice the voltage of the A. C. source, to be produced across terminals 24 and 25, this voltage being produced substantially simultaneously with the closing of switch 9 because of the negligible charging time of condensers 22 and 23. since relay contacts 29 are originally closed, current will flow from terminal 25, through lamp 29, resistor 39, contacts 29, filament 3, and winding 21, back to terminal '24, this current serving to heat filament 3 to the temperature of thermionic emission. The flow of current through winding 2? will energize relay 28 to open its contacts 29, thus opening the circuit through said winding, causing said relay to be deenergized to again close contacts 29 and complete the circuit through said winding to again energize it. Resistor 39 serves to limit the current through filament 3 during the starting operation. As will be appreciated, filament 4 serves as the anode for the discharge through tube 1, since it is connected to the positive terminal 25. As filament 3 is being heated through the above-described circuit, relay 23 will be rapidly, and successively, energized and deenergized, opening and closing contacts 29 in a buzzing fashion.

When filament 3 has been heated to the temperature of thermionic emission, a sufiicient num ber of ions willbe produced in bulb 2 to cause the main discharge to be started between filaments 3 and 4, a voltage high enough to estab: lish this discharge being supplied by circuit 8, When current begins to flow in the discharge path between electrodes 3 and 4, the circuit ine cluding contacts 29 and resistor 33 is effectively bypassed, so that the buzzing of relay 28 is stopped, and enough current flows in this discharge path to maintain relay 28 energized, and ontacts 23 open. With contacts 23 open, the heating circuit for filament 3 is opened, so that th'ere'aiter' filament 3 is heated by ionic bomherdm nt in. the usua mann "Lamp 25 serves as a ballast resistor, limiting the current through lamp l during operation. By choosing the proper value of resistance for resistor 31), the filament 3 may be heated rapidly, so that the lamp l may be started practically in tantaneou ly; sinc tube l2 and 3 e u no externa o r e for he g he a odes, a amount of power is drawn from th .A- (2- sou e Sin e. the discharge in lamp l unidirectional on account of D. C. being utilize therefor, flic er of the d s a e is rem ve o el minated,

' In g 2, another embodiment of this invention s shown and. in said figure, similar pa t have been denoted by the same reference numorals as. in Fig, 1. When switch 9 is closed, it ener izes the primary winding; 31 of a transmi er 38,-. .A s c nda y windi g 39- n izes ci rcqi t ich i simi ar o that of Fi 1, n thereby supplies high voltage direct current. to termin s 24 and .2

' A ili or'esce t amp has filaments 32 and 3.3. sealed into opposite ends thereoi, and a second fluoresc nt lamp 3 has filaments. 3.5 and 3,5 sealed to opposite. ends, thereof. Filament 33 er ized by being connected across. a secondwmding 40a. of transiormer 38,, and filament A a nergized by fii lg eflnnected across. secondary winding 40b. oi transformer 38..

Negative terminal 24 is connected, through winding 2.1 of r lay 28 nd an. nductance. 4!, t one side. of filament 35 Filament 36, is. connected to iilament 33 bymeans of lead 42. Filament 32 connected, to positive terminal 25 through a ballast, resistor 43, of, for example, 40 ohms...

Contact 2341, one. of a pair of normally-closed contacts 233 o e y 2. is. connected to resistor 4,3.throu h another resistor 44,, which latter may or c'onr n ence be built int relay- 28, Conta t 23c, is also, connected, through a'condenser 45, to filamentv 36., while contact 21%. is connected, to fil m nt 35.

,hen switch 9, is closed, terminal 25 becomes the. positive terminal for D. C., as stated above,

and current flows through resistor 43, resistor 44., normally-closed contacts 29a and 29b, inductance M... an in i to gati termi a l gizging relay 28. tofopen its contacts. 29... When sw tch, 9. lose th he ting. cir uits. or files merits 33 and 35 are completed. When contacts 23 are opened by the energization of relay 28,

the series circuit through inductance 41 and winding 21 is broken, so that a high-voltage in ductive kick, due to the decay of current in these inductances, appears across these inductances, driving the potential at each end of lead 46 negative with respect to terminal 24. When contacts 29 of relay 2B are closed, a circuit is completed as follows between terminals 25 and 24 of the source: terminal 25, resistor 43, resistor 44, contact point 23a, contact point 2%, inductance 4|, winding 21, to terminal 24. Inductance 41 and winding 2'! both have a negligible resistanc as compared to resistors 44 and 43, and, as a result, current flow in this circuit produces substantially all of the voltage drop across resistors 43 and 44, so that, while contacts 23 are closed, point 29a has a potential which is substantially the same as that of terminal 24, and, assuming condenser 45 to be originally uncharged, the potential at each end of lead 42 is also substantially the same as that of terminal 24. When contacts 29 are opened by the energization of relay 28, the potential of point 29a quickly rises to the potential of terminal 25, which is positive with respect to terminal 24. When the potential of point 29c thus rises, that at each end of lead 42 will rise along with it, and to the same value, assuming condenser 45 to be originally uncharged.

It will be seen that the voltage applied to lamp 34 is the diiierence of potential between leads 42 and 46. When contacts 29 are opened, the potential of lead 46 Will go negative with respect to terminal 24, while the potential of lead 42 will go positive with respect to said terminal. Thus, there will be a large difference of potential between leads 42 and 46, sufilcient to start the discharge in lamp 34.

,When the dischar e has started in lamp 34, a charging circuit will be completed as follows for condenser 45: terminal 25, resistor 43, resistor 44, point 29a, condenser 45, discharge path 35-35, lead 46, inductance 4t, winding 21, to terminal 24. Current will flow in this circuit, charging condenser 45 with a polarity such that point 29a, becomes positive with respect to lead 42. The voltage across condenser 45 s p ied to l mp. 3!, since lead 42 is connected to the right-hand side of con enser 45 a d fil m t While th left-hand side of. condenser 45 is connected through point 29c. and resistor 4.4. to filament 32 The voltage across condenser 45' rises as it, is char ed, un il anoint. is reach d at. whi h the voltage thereacross is, sufficient, to Start, the dischar e in lamp 3L, When the discharge. is establi hcd in lamp. 3i, thev voltage across condenser 45 falls. to, the voltage. drop of the dischargein said, lamp, because condenser 45 will not pass directv current.

When;v the, discharges have. been started in lamps, 3!, and 34, as will be seen, pa ths 3233 and 36-35, are in series with each other acrossthe Source. The, establishment. or, current flow in both paths 32-33 and 3.!i.35 establishes a hold.- ing circuitior. maintaining relay 2& energized and contacts 29 open, this circuit being traced asiole lows: terminal 25, resistQr 43,, path 32-33,, lead 42,, path 36:45". l d. 4.6, inductance 4i,. 1 .i 2-1., to terminal 24., The voltage. supplied. by circuit & at, terminals. 24 and 25 is sufiici'ent to aint in discharges hr gh tub s. El and will series, During operation of th lamps, and also duri g tarting her o fi ments. 3.2 and 35.. act as an es. for the disc ar s wh e. lame t 33 and 35; are continuously supplied with heating current from the A. C. source and act as; cathodes or electron emitters;

When switch 9 is actuated to extinguish the lamps, the discharges in paths 32-33 and 36-35 will cease and relay 28 will be deenergized in preparation for the next operation. Condenser 45 will retain its charge, because there is no discharge path for it, and therefore the charge will leak 01f of it only extremely slowly, if at all. The charge retained by condenser 45 produces a voltage thereacross which causes the potential of lead 42 to not attain as high a positive value when contacts 29 are opened as it would if said condenser were originally discharged. However, the value of inductance of element 4|, and the speed of operation of relay 28, are made such that the potential of lead 46 goes sufiiciently negative, when relay 28 is energized, to provide the proper potential difference across lamp 34, even though the potential of lead 42 may not be as highly positive at this time as it would have been if condenser 45 had originally been discharged.

Resistance 44, which may, for example, be built into relay 28, serves as a limiting resistor to protect relay 28 from a large initial inrush of current when switch 9 is first closed. Ballast resistor 43 limits the current flowing through lamps 3| and 34 during operation thereof, while inductance 4|, in addition to its function stated above, has the additional function of keeping the circuit from oscillating.

In the circuit of Fig. 2, a minimum amount of power is expended in the ballast resistor 43, because of the low resistance of said resistor. In Fig. 2, as in Fig. 1, flicker will be eliminated, because of the unidirectional character of the discharge due to the direct current supplied to the lamps. The discharge in lamps 3| and 34 may be started substantially instantaneously because of the rapid energization of relay 28 and the consequent kick applied to the lamps. It has been found that the total voltage drop in a lamp of the type of this invention is the sum of three voltage drops: the cathode drop, the anode drop, and the drop in the positive column. Most of the light produced is a result of the drop in the positive column. Therefore, if the tube is lengthened until the positive column is of such length that the voltage drop therein is almost equal to the voltage available, the lamp will be operated at a higher efficiency, for the production of light.

Of course, it is to be understood that this invention is not limited to the particular details as described above, as many equivalents will suggest themselves to those skilled in the art. It is accordingly desired that the claims be given a broad interpretation commensurate with the scope of this invention within the art.

What is claimed is:

1. A gaseous discharge device starting circuit, comprising a gaseous discharge device having a pair of filaments, a relay having an operating winding and a pair of normally closed contacts, an inductance, a voltage source, means connecting said winding and said inductance in series between one terminal of said voltage source and one of said filaments, means connecting said contacts in series between the other terminal of said source and said one filament, and capacitive means connected between said other terminal and the other of said filaments.

2. A fluorescent lamp circuit including, in combination, a rectifying and voltage-doubling circuit having a pair of output terminals and a pair of input terminals, a source of alternating current, means connecting said input terminals to said source of alternating current, a first gaseous discharge fluorescent lamp having a pair of filaments, a second gaseous discharge fluorescent lamp having a pair of filaments, means connect! ing one of the filaments of said first lamp to one of the filaments of said second lamp, means connecting the other filament of said first lamp to one of said output terminals, and means connectingthe other filament of said second lamp tothe other of said output terminals.

3. A gaseous discharge device circuit including, in combination, a rectifying and voltage-doubling circuit having a pair of output terminals and a pair of input terminals, a source of alternating current, means connecting said input terminals to said source of alternating current, a gaseous discharge device having a pair of filaments, a relay having an operating winding and a pair of normally closed contacts, an inductance, means connecting said winding and said inductance in series between one of said output terminals and one of said filaments, means connecting said contacts in series between the other of said output terminals and said one filament, and capacitive means connected between said other output terminal and the other of said filaments.

4. Agaseous discharge device circuit including, in combination, a rectifying and voltage-doubling circuit having a pair of output terminals and a pair of input terminals, a source of alternating current, means connecting said input terminals to said source of alternating current, a first gaseous discharge device having a pair of filaments, a second gaseous discharge device having a pair of filaments, means connecting one filament of said first lamp to one filament of said second lamp, a relay having an operating winding and a pair of normally closed contacts, an inductance, means connectingsaid winding and said inductance in series .between one of said output terminals and the other filament of said first device, means connecting said contacts in series between the other of said output terminals and said other filament of said first device capacitive means connected between said other output terminal and said one filament of said first device, and means connecting said other filament of said second device to said other output terminal.

5. A fluorescent lamp circuit including, in combination, a gaseous discharge fluorescent lamp having a pair of filaments, a relay having an operating winding and a pair of normally closed contacts, a voltage source, means connecting said winding in series between one terminal of said voltage source and one of said filaments, means for heating said one filament to emission temperature, means connecting said contacts in series between the other terminal of said source and said one filament, capacitive means connected between said other terminal and the other of said filaments, and a shunt circuit connected across said capacitive means between said other terminal and said other filament.

6. A fluorescent lamp circuit including, in combination, a first gaseous discharge device having a pair of filaments, a second gaseous discharge device having a pair of filaments, means connecting one filament of said first device to one filament of said second device, a relay having an operating winding and a pair of normally closed contacts, a voltage source, means connecting said winding in series between one terminal of said voltage source and the other filament of said first device, means for heating said other filament of said first device and said one filament of said second device to. emission temperature, means connecting said contacts inseries between the othertemiinal of said sourc -and said other filenient of said first device, capacitive means connected between said other terminal and said one filament ofsaid first device, an means connect ing the other filament of said second device to said other terminal, whereby the interelectrode path of said second device provides a shunt cir cuit connected across saidcapacitive means between said other terminal and said one filament ofsaid first device;

7; A gaseous discharge device circuit. including, in combination,- a rectifying and voltage-doubling circuit havinga pair of output terminals and a pair of inputterminals, a source of alternating current, means connecting said input terminals to said source oi alternating, current; a gaseous discharge device having a. pair or filaments, a relay having an operating winding and a pair. of normally closed contacts means, connecting said winding inseries between one ofv said output terminals and one of said filaments,- means for heating said one filament to emission temperature; means connecting said contacts in series between the other of said output terminals and said. one filament, capacitive means connected between said other output terminal and the other of said filaments, and a shunt circuit connected across said capacitive means between said other output terminal and said other filament-.-

8'. A- fiucrescent: lamp circuit including, in com. bination, a rectifying and voltage-doubling oircuit having a pair'of. output terminals anda pair or input terminals, a source of alternating current, means connecting said. input terminals to said source oi alternating current, a first gaseous discharge fluorescent lamp having a pair of filamantav a second: gaseous discharge fluorescent lamp having a pair 01- filaments, means; connectterminals and said other filament of said first lamp; capacitive means connected between said other output terminal and said on filament of said first lamp; and means connecting the other filament oi said second lamp to said other output terminal, whereby the interelectrode path of said second lamp provides a shunt circuit con nected across said capacitive means between said other output terminal and said one filamentof said first'lampi w PAUL W. STUTSMAN;

References Gited in the file of this patent UNITED STATES PATENTS Number Name Date $522 563 flempbeil June 27, .44 1,275,890 Flannery .i Aug. 13, 19 8 1,984,4fi9 Mutsaers or 15cc. 13, 1934 2,056,661 Foulke r s s Oct. 6 1936 211%;393 fiirey flesh. Sept. 6, i938 2,1553%16 Babb -11 Apr. 25, 1939 2,180,815 Meier -1 Nov. 21, 1939 2,181,294 Biggs Nov. 28,1939 2,266,619 Campbell -s 1 Dec. 16, 1941 2,465,059 Campbell Mar. 22 1949 FOREIGN PATENTS Number 7 Country Date 311,282 Great Britain 1---- Aug. 7,- 1930 

